With the leaders of the United States and China set to meet this week, experts say this is the best time for President Xi Jinping to negotiate. The US is busy with wars in the Middle East, and President Donald Trump’s approval rating is cratering at home: he is desperate for a win, which could give China the upper hand.Trade between the world’s two largest economies has been disrupted since Trump returned to office last year and unleashed a series of tariffs on the world, imposing some of the highest rates on China, 145 percent at one point.Recommended Stories list…